Much water and energy is wasted in residential buildings, due to poorly designed, poorly installed—and therefore poorly functioning—hot water delivery systems. Homes built in the United States today are typically larger than ever before and include a number of hot water fixtures not seen a generation ago, such as second and third bathrooms and spa-style showers. And water heaters are typically far away from many of the hot water fixtures. All this adds up to long waits for hot water at fixtures and water and energy down the drain to no purpose (see “Hot Water Runs Cold,” HE Mar/Apr ’05, p. 28).
One solution to water and energy waste is to deliver hot water quickly to where it is needed. By bringing water quickly to fixtures that are far from the water heater, a demand-controlled pumping system minimizes the waste of water and energy running down the drain while someone waits for the hot water to arrive.When signaled to do so by a hot water user using a push-button control, an electronically demand-controlled pumping system sends cold water back to ...